We all have our strange little hobbies.

I keep an eye out for mentions of a shonky old estimate on the social cost of alcohol. When it turns up, pulling on the thread can be great fun.

Back when I was an academic at the University of Canterbury, Sir Geoffrey Palmer was leading a review into alcohol legislation. He cited a dodgy-sounding BERL figure on the purported social cost of alcohol as motivation for some of his work. Matt Burgess and I dug into BERL’s figure.

We found a shambles. The number was largely based on counting costs that drinkers impose upon themselves, including their own spending on alcohol, and mismeasuring other costs. We published our critique and let the Ministry of Health, who had co-commissioned the number, know that it was not reliable.

Nevertheless, it keeps turning up. Big numbers are useful in pushing political agendas regardless of whether the method used to produce them stacks up.

Last year, the Public Health Agency commissioned NZIER and Allen + Clarke to review the alcohol levy. The report cited the BERL figure, and rather cryptically noted that the figure had been criticised. Nothing about the nature of the critique was mentioned, but the bibliography cited our work on it.

It looked like the report might have once had more fulsome discussion of the critique. Why else include it in the bibliography? So I started to pull on the thread.

It has taken months of off-and-on OIA work and intervention from the Ombudsman. And the Public Health Agency continues to refuse to provide the early draft that would show what was expunged.

But they did release one comment on the earlier draft. That comment warned against relying on my critique because “Eric Crampton is one person…. He is part of the NZ Initiative which is pro business … I don’t think it is appropriate to be including his views.”

It’s an insight into how the Public Health Agency works. If work commissioned by independent agencies include politically inconvenient bits, those bits may be culled before the work can make it to the Minister.

Chasing these sorts of things down might be a strange hobby. But it can be fun.

And if a government is looking for ways of saving money in the leadup to a budget, a Public Health Agency whose reports require public health warning labels might be worth a look.